(Lianja) JWE using "dir" Direct use of Shared Symmetric Key

Demonstrates how to create a JWE using the "dir" alg -- which is to directly use a shared symmetric key.

Note: This example requires Chilkat v9.5.0.66 or greater.

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// This requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

// Note: This example requires Chilkat v9.5.0.66 or greater.

lcPlaintext = "Live long and prosper."

loJwe = createobject("CkJwe")

// First build the JWE Protected Header..
loJweProtHdr = createobject("CkJsonObject")
loJweProtHdr.AppendString("alg","dir")
loJweProtHdr.AppendString("enc","A128GCM")

// Don't forget to actually provide the protected header to the JWE object:
loJwe.SetProtectedHeader(loJweProtHdr)

// The JWE is to use 128-bit AES GCM encryption as specified by the "enc" parameter.
// Given that the "alg" = "dir", we are to directly specify the AES GCM key.
// (It is assumed that the decrypting side also has knowledge of the direct key to be used..)

// Our key will be these 16 hex bytes: 000102030405060708090A0B0C0D0E0F

// The SetWrappingKey method is also used for "dir" direct keys.
// However, if there are multiple recipients, they must all share the same CEK (Content Encryption Key),
// which is specified by calling SetWrappingKey with an index of 0.

lnRecipientIndex = 0
loJwe.SetWrappingKey(lnRecipientIndex,"000102030405060708090A0B0C0D0E0F","hex")

// Encrypt and return the JWE:
lcStrJwe = loJwe.Encrypt(lcPlaintext,"utf-8")
if (loJwe.LastMethodSuccess <> .T.) then
    ? loJwe.LastErrorText
    release loJwe
    release loJweProtHdr
    return
endif

// Show the JWE we just created:
? lcStrJwe

// Decrypt the JWE.
loJwe2 = createobject("CkJwe")
llSuccess = loJwe2.LoadJwe(lcStrJwe)
if (llSuccess <> .T.) then
    ? loJwe2.LastErrorText
    release loJwe
    release loJweProtHdr
    release loJwe2
    return
endif

loJwe2.SetWrappingKey(0,"000102030405060708090A0B0C0D0E0F","hex")

// Decrypt.
lcOriginalPlaintext = loJwe2.Decrypt(0,"utf-8")
if (loJwe2.LastMethodSuccess <> .T.) then
    ? loJwe2.LastErrorText
    release loJwe
    release loJweProtHdr
    release loJwe2
    return
endif

? "original text: "
? lcOriginalPlaintext

// Sample output:
// eyJhbGciOiJkaXIiLCJlbmMiOiJBMTI4R0NNIn0..20HX5Huc7f1nQC4pBUtiCQ.axFZIxtZy5j0ifJQUzGXLKIpsBuxJA.eBrOC-NrsreN6JeGuOPk1g
// original text: 
// Live long and prosper.


release loJwe
release loJweProtHdr
release loJwe2